+/**
+ * Splits out individual email patches from `paths`, where each path is either
+ * a mbox file or a Maildir. Returns 0 on success, -1 on failure.
+ */
+static int split_mail_mbox(struct am_state *state, const char **paths)
+{
+ struct child_process cp = CHILD_PROCESS_INIT;
+ struct strbuf last = STRBUF_INIT;
+
+ cp.git_cmd = 1;
+ argv_array_push(&cp.args, "mailsplit");
+ argv_array_pushf(&cp.args, "-d%d", state->prec);
+ argv_array_pushf(&cp.args, "-o%s", state->dir);
+ argv_array_push(&cp.args, "-b");
+ argv_array_push(&cp.args, "--");
+ argv_array_pushv(&cp.args, paths);
+
+ if (capture_command(&cp, &last, 8))
+ return -1;
+
+ state->cur = 1;
+ state->last = strtol(last.buf, NULL, 10);
+
+ return 0;
+}
+
+/**
+ * Splits a list of files/directories into individual email patches. Each path
+ * in `paths` must be a file/directory that is formatted according to
+ * `patch_format`.
+ *
+ * Once split out, the individual email patches will be stored in the state
+ * directory, with each patch's filename being its index, padded to state->prec
+ * digits.
+ *
+ * state->cur will be set to the index of the first mail, and state->last will
+ * be set to the index of the last mail.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int split_mail(struct am_state *state, enum patch_format patch_format,
+ const char **paths)
+{
+ switch (patch_format) {
+ case PATCH_FORMAT_MBOX:
+ return split_mail_mbox(state, paths);
+ default:
+ die("BUG: invalid patch_format");
+ }
+ return -1;
+}
+